Pneumatic Conveying Control Methods for Process Automation

How level sensors can bring greater control and automation when combined with VOLKMANN UK pneumatic vacuum conveying

When it comes to pneumatic vacuum conveying, engineering the right control measure for the process is critical. Greater control and automation over material transfer will boost production efficiency, remove bottlenecks and help avoid unnecessary downtime. Automation remains a key talking point when visiting sites, with manufacturers seeking a consistent and controlled process.

With pneumatic conveying systems control is typically achieved by 1 of 3 things, or in some cases, a combination of the three – manual timer settings, level sensors, or load cells.

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Pneumatic conveying systems are widely used across food processing, pharmaceuticals, chemicals and powder handling applications where reliable and automated material transfer is essential. Selecting the right control method can improve process efficiency, reduce compressed air waste and support greater automation across manufacturing operations.

Understanding pneumatic conveying control methods

Manual timer control in pneumatic conveying systems

The most basic method of control is through manual timer settings. For example, on VOLKMANN’s pneumatic timers, the suction and discharge settings can be adjusted manually to control the amount of product conveyed per cycle.

This offers an effective level of control and is ideal for operation in ATEX zones or for straight-forward processes handling a single material. Though, it’s important to note the quantity of product conveyed per cycle may vary depending on the pickup method and the product itself- for example, when using a suction lance, the quantity may be impacted by the operator manoeuvring the lance.

Using an RNT provides greater consistency as the product naturally flows to the bottom of the cone, with discharge aids available where required.

“Greater control and automation over material transfer will boost production efficiency, remove bottlenecks and help avoid unnecessary downtime.”

Manual control relies on the operator switching the system on and off at the pneumatic timer. Once turned on, the unit will continue cycling and conveying batches of product, until it is manually stopped – even if there is no product left in the pickup location. Likewise, the receiving location will be fed until the system is switched off. Meaning, this control method still requires an operator to oversee the process to ensure the receiving vessel is not overfilled.

This method of control only requires a pneumatic timer, meaning the system remains fully pneumatic and is safe for ATEX dust zones. Material transfer is controlled and efficient but full automation is limited as an operator is required to monitor the system at each stage.

Limitations of manual pneumatic conveying control

While manual timer control offers a simple and cost-effective solution for pneumatic conveying systems, it can introduce several operational limitations as production demands increase. In many manufacturing environments, greater process consistency and automation are now required to support efficiency targets, reduce downtime and minimise material waste.

One of the main challenges with manual control is operator dependency. The conveying process relies on an operator to start and stop the system at the correct time, monitor product levels and ensure receiving vessels do not become overfilled. This increases the likelihood of human error and can create inconsistencies between production shifts or batches.

Manual timer settings can also lead to inconsistent batch transfer rates. Variations in material characteristics, product bulk density or the way operators handle suction lances can affect the quantity of product conveyed during each cycle. This inconsistency may impact downstream processes and make it more difficult to maintain stable production conditions.

Another important consideration is compressed air waste. If the conveying system continues operating after the product supply has been depleted, compressed air is consumed unnecessarily. Over time, this can increase operational costs and reduce overall energy efficiency across the manufacturing process.

Production inefficiencies can also occur when operators are required to continuously supervise the conveying process. Time spent manually monitoring equipment could otherwise be allocated to higher-value production activities. In fast-paced manufacturing environments, reducing manual intervention is becoming increasingly important for improving productivity and maintaining consistent output.

As production volumes grow, manual control systems may also present limited scalability. Expanding operations or integrating additional conveying lines often requires more advanced automation and process control. Incorporating level sensors and automated controls can help manufacturers create a more flexible and scalable pneumatic conveying system capable of supporting future operational requirements.

Why level sensors improve pneumatic conveying automation

For greater control and a higher level of automation, level sensors can be installed at the pickup location, inside the conveyor itself, and in the receiving location. When integrating a level sensor, a more advanced control system is required. For VOLKMANN UK, this is our ET range of timers. They can accept a 24V control signal(s) from one or multiple level sensors installed in any of the following locations.

Using level sensors at the product pick-up point

For product pickup, high level or low-level sensors can be included. A low-level sensor is often the preferred method, and this will send a stop signal to the timer when the sensor is covered, indicating the need for additional product, or the end of a batch.

Having this sensor included will ensure that no compressed air is wasted if the system is left running when the product runs out. A high-level sensor works in a similar way, though this will require the hopper to be constantly full to convey product and the level will need to be maintained. In practise a high-level sensor is more commonly used to indicate when the hopper needs filling.

“Level sensors offer a practical way to achieve a higher level of automation in pneumatic conveying.”

Internal level sensors for conveyor optimisation

A high-level sensor can also be used in the conveyor body to replace the suction time. This would allow the system to keep filling the unit until this sensor is covered. Once covered, the suction cycle stops and the product is discharged.

This allows for a more efficient and consistent transfer as the conveyor will fill to the max volume each cycle, meaning the transfer rate will be optimised, while moving a consistent volume of product each time. VOLKMANN UK usually recommend that this approach is implemented when various products with a range of bulk densities are to be conveyed using the same system.

This enables us to maximise the transfer rate for each of the products, while eliminating the risk of overfilling the unit. Without this sensor, the control settings on the timer would need changing each time the product to be conveyed is changed.

Preventing overfilling at the receiving location

Similar to product pick up, high level and low-level sensors can be included in the receiving location. A high-level sensor is selected to ensure the receiving hopper is not overfilled. It is uncommon to have a low-level sensor here by itself, but it may be needed if only small amounts of product are required in the receiving vessel to not impact the downstream process. In some cases, both sensors can be included, this is typically done when a certain level is to be maintained in the receiving location.

VOLKMANN UK’s standard ET timers accept one control signal from each sensor. When multiple sensors are required, our ET advanced timer can be used. This will control 3 sensors integrated in the system simultaneously.

Benefits of automated pneumatic conveying systems

Automated pneumatic conveying systems provide manufacturers with greater process control, improved efficiency and a more reliable material handling operation. By integrating level sensors and advanced control systems, manufacturers can reduce manual intervention while achieving a more consistent and optimised conveying process.

One of the key advantages of automation is reduced operator intervention. Once level sensors and automated controls are integrated into the conveying system, the transfer process can respond automatically to changes in product levels at the pickup and receiving locations. This minimises the need for operators to continuously monitor the system, helping to reduce labour demands and allowing production teams to focus on other critical tasks.

Automation also helps deliver improved transfer consistency. Using level sensors to control suction and discharge cycles enables the conveyor to operate with more precise and repeatable fill levels. This creates a more stable and predictable material transfer process, which is especially important in applications where downstream equipment relies on consistent product feed rates.

Another major benefit is improved energy efficiency through compressed air optimisation. Pneumatic conveying systems can consume significant amounts of compressed air, particularly if systems continue operating unnecessarily. Automated controls help ensure the conveying process only runs when required, reducing wasted compressed air and lowering operational energy costs.

Reducing unnecessary system operation can also help minimise equipment wear and reduce downtime. By preventing overfilling, empty running and inconsistent conveying cycles, automated systems can support more reliable production performance while helping to reduce maintenance requirements and unplanned production interruptions.

Better process repeatability is another important advantage, particularly for manufacturers handling multiple products or varying batch sizes. Automated conveying systems can maintain consistent operating parameters across production runs, improving quality control and reducing process variation.

Modern pneumatic conveying automation can also support integration with Industry 4.0 manufacturing environments. Advanced control systems and level sensors can be connected to wider plant monitoring and control platforms, enabling improved process visibility, data collection and automated production management. This allows manufacturers to move towards smarter and more connected manufacturing operations while improving overall process efficiency.

Choosing the best pneumatic conveying control system

Control and automation requirements will always vary depending on the industry, requirements and budget. Level sensors offer a practical way to achieve a higher level of automation in pneumatic conveying. They can significantly improve efficiency and reduce the need for operator attention when using pneumatic conveying systems.

FAQ's

What is pneumatic vacuum conveying?

Pneumatic vacuum conveying is a method of transferring powders, granules and bulk materials through a closed pipeline system using negative pressure or vacuum. The system safely and efficiently moves materials between processing stages while helping to reduce dust, contamination and material loss. Pneumatic vacuum conveying systems are widely used in industries including food processing, pharmaceuticals, chemicals and additive manufacturing.

How do level sensors work in pneumatic conveying systems?

Level sensors are used to monitor material levels at key points within a pneumatic conveying system, including the product pickup location, the conveyor body and the receiving vessel. The sensors send signals to the control system when product levels reach specific points, allowing the conveying cycle to automatically start, stop or discharge material. This helps improve automation, prevent overfilling and optimise conveying efficiency.

What are the benefits of automated pneumatic conveying?

Automated pneumatic conveying systems can improve process efficiency, reduce operator intervention and provide more consistent material transfer rates. By integrating level sensors and advanced controls, manufacturers can reduce compressed air waste, improve process repeatability and minimise the risk of downtime caused by overfilling or inconsistent conveying cycles. Automation can also support integration with Industry 4.0 manufacturing systems for improved process monitoring and control.

Can pneumatic conveying systems operate in ATEX zones?

Yes, pneumatic conveying systems can be designed for safe operation in ATEX dust zones. Fully pneumatic control systems are commonly used in hazardous environments because they do not require electrical components within the ATEX zone. Depending on the application, additional safety measures and certified components may also be required to ensure compliance with ATEX regulations and site-specific safety requirements.

How do you prevent overfilling in conveying systems?

Overfilling in pneumatic conveying systems is commonly prevented using high-level sensors installed in the receiving vessel or hopper. When the material reaches the specified level, the sensor sends a signal to the control system to stop or pause the conveying cycle. This helps protect downstream equipment, maintain stable production conditions and reduce material waste or process interruptions.